1. Technical Field
The present specification describes a liquid discharging head, a liquid discharging device, and an image forming apparatus, and more particularly, a liquid discharging head, a liquid discharging device, and an image forming apparatus for forming an image on a recording medium by discharging liquid onto the recording medium.
2. Discussion of the Background
An image forming apparatus, such as a copying machine, a printer, a facsimile machine, a plotter, or a multifunction printer having two or more of copying, printing, scanning, and facsimile functions, forms an image on a recording medium (e.g., a sheet) by a liquid discharging method. For example, a liquid discharging head (e.g., a recording head) included in a liquid discharging device discharges liquid (e.g., an ink drop) onto a conveyed sheet. The liquid is adhered to the sheet to form an image on the sheet.
The image forming apparatus and the liquid discharging device may be used in an industrial system including a printing device and metal wire. Accordingly, the image forming apparatus and the liquid discharging device are requested to form a high-quality image at a high print speed.
To output a high-quality image, the image forming apparatus and the liquid discharging device may include an increased number of nozzles arranged at high densities, liquid chambers may be arranged with a decreased distance provided between the adjacent liquid chambers, and energy may be applied at an increased frequency.
In addition, to form an image at a high print speed, the image forming apparatus and the liquid discharging device may include a long liquid discharging head (e.g., a line-type head) covering a whole width of a sheet.
One example of the liquid discharging head includes a nozzle, a liquid chamber, and a pressure generator. The nozzle discharges a liquid drop. The nozzle is connected to the liquid chamber. The pressure generator generates pressure for pressing liquid in the liquid chamber. Namely, pressure generated by the pressure-generator presses liquid in the liquid chamber, so that the nozzle discharges a liquid drop. The pressure generator generates pressure using a thermal method, a piezoelectric method, or an electrostatic method.
In the piezoelectric method, a piezoelectric element is adhered to a base (e.g., a metal member). A plurality of piezoelectric elements or a plurality of heads including a piezoelectric element is arranged to form a long head such as a line-type head.
In the thermal method, a plurality of boards including a thermal conversion-element is arranged on a base to form a long head such as a line-type head.
To manufacture a long, line-type head without increasing the size of the head, a plurality of piezoelectric elements may be disposed on a single base. In this case, surface grinding is performed on the single base to give the base a flat surface over which there is no more than about a 20 μm difference in height between a thickest part and a thinnest-part of the base.
However, the desired flatness may not be obtained over the whole base due to thermal deformation during processing. Consequently, the base may be warped and a thickness of an adhesive applied between the base and the piezoelectric elements may vary, causing faulty adhesion. As a result, the piezoelectric elements may not be properly adhered to a vibration plate.
In the thermal method, a board including a thermal conversion element is adhered to a base, and a nozzle plate is adhered to the board. Therefore, a nozzle may not properly discharge a liquid drop onto a sheet if the base is warped. For example, the nozzle may not discharge a liquid drop in a uniform direction. As a result, the liquid drop may spread on the sheet.